The problem to be solved by this invention is to provide an improved cooling device to a semiconductor chip using multiple fans and heat sinks. This cooling device has multiple fans connected in a redundant mode such that if one fan malfunctions, the remaining fans will spin up to make up the lost of air flows to the heat sinks. The current fan-heatsink uses only one fan and has no redundant feature.
(1) U.S. Pat. No. 5,309,983—“Low Profile Integrated Heat Sink and Fan Assembly”, describes a heat sink with straight fins and a fan integrated in a cavity in the fin area. The base of the heat sink is a flat, solid plate and the fins are straight fins. The fan has air inlets on the top surface of the fan. Air is moving through the fan and the spacing between fins at two opposite directions. The solid heat sink base does not provide a compliant interface to the heated surface underneath and the air flows are restricted to own two directions which are inherently inefficiency. Furthermore, the air inlets are on one surface only.
(2) U.S. Pat. No. 5,502,619—“Heat Sink Assembly for Computer Chips”, teaches another type of fan-heatsink assembly which has the fins stacked up by a plurality of sheets with openings and the fan placed on the top of the stacked sheets. This stacking method of making the fins for the heat sink will impede the heat flow from the heated source underneath the heat sink and hence rendering it inefficient for heat transfer. This heat sink has a solid base and the fan has inlets at the top surface only.
(3) U.S. Pat. No. 5,584,339—“Heat Sink Assembly for the Central Processor of Computer”, describes another type of fan-heatsink assembly which has a fan with cover placed in the middle of the heat sink that has post-like fins. The post-like fins will give air multiple air flow paths with the heat sink but the fan still has one inlet on one surface. The base of the heat sink is also a solid plate.
(4) U.S. Pat. No. 5,785,116—“Fan Assisted Heat sink Device”, teaches a heat sink assembly having heat sink housing surrounding the fan. Cold air enters the heat sink house near the top of the house and hot air exits the house from the bottom end in all the directions. Since there is no provision to separate the cold and hot air, air mixing may happen and the efficiency of the cooling device will degrade. Furthermore, the base of the heat sink is a solid plate which cannot provide compliant interface to the hot surface underneath. The hot air coming out from the heat sink device will add heating effects to the surrounding chips. This is considered undesirable.